9 more scarves and small corgi cleanup

Adds 9 more scarves (light blue, dark blue, orange, yellow, purple,
white, black, zebra and christmas).
Cleaned up corgi code a little bit, specially the parts involving icon
updates. Fixes a bug where adding a hat to a dead corgi didn't make you
drop your hat and created duplicate items. Makes corgis only use one
head/back mob sprite and rotate it appropriately. Call
regenerate_icons() only when needed now, instead of doing so every tick
on Life().